This invention relates to a staggered needle tufting machine and more particularly to a needle plate member for supporting the base fabric in a staggered needle tufting machine.
In a conventional multiple needle tufting machine, the needle plate is provided with a plurality of uniformly spaced straight fingers extending from one edge of the plate in the direction of the fabric feed, or rearward, so that each finger extends between and beyond an adjacent pair of needles. These fingers are adapted to provide a support for the portion of the base fabric in the path of the needles and are spaced to permit free reciprocation of the needles between the fingers. In a conventional multiple needle tufting machine, the needle plate fingers are uniformly spaced at the same gauge as the needles.
Furthermore, a conventional needle plate finger has a rectangular cross-section, with its short dimension transverse, and its long dimension vertical. Thus, each cantilevered needle plate finger has substantial depth to provide sufficient strength to support the base fabric as the fabric is penetrated by the needles. Moreover, the short transverse dimension of each needle plate finger is desirable so that the needles can be spaced closer together to achieve finer gauges.
Generally speaking, in order to form tufted loops of low pile having as short a nap as possible, the hooks are mounted to move as closely as possible beneath the bottom surfaces of the needle plate fingers, and the height of the bills of the loopers is reduced to a minimum. To reduce the depth of conventional needle plate fingers would materially reduce their strength and rigidity to a degree that the needle plate fingers would not adequately support the base fabric as the fabric is penetrated by the needles carrying the yarns.
Examples of various types of prior art needle plates are shown in the following U.S. Pat. Nos.
______________________________________ 2,975,736 J. L. Card Mar. 21, 1961 2,976,829 R. T. Card Mar. 28, 1961 3,019,748 J. L. Card Feb. 6, 1962 3,064,600 R. T. Card Nov. 20, 1962 3,241,507 G. D. Dedmon, et al Mar. 22, 1966 (Base plate 62-FIG. 4) 3,361,095 J. T. Short Jan. 2, 1968 3,398,708 R. T. Card Aug. 27, 1968 ______________________________________
Both J. L. Card patents disclose typical conventional needle plates having longitudinal grooves receiving elongated needle plate fingers of rectangular cross-section having a greater depthwise dimension than its transverse dimension.
The three R. T. Card patents disclose needle plates having needle plate fingers of varying configurations to accommodate narrow gauge, staggered needles.
The Dedmon et al patent discloses a "usual base plate 62" in which the needle plate fingers appear to have been formed by milling the trailing edge of the base plate to produce long needle plate fingers of substantial depth.
The Short patent discloses a needle plate of substantial thickness having a plurality of uniquely shaped recesses in the trailing edge of the needle plate especially formed to accommodate hollow, cylindrical needles of the type through which a fluid is discharged to carry the yarn through the hollow needle and fabric.
None of the above patents disclose a needle plate which is capable of producing very low pile loops in a tufted fabric.
There has been a trend in the tufting industry toward the production of tufted fabrics having a very low, as well as dense, pile, simulating products resembling velvet. The height of the tufted loops have been reduced by reducing the height of the bills of the looper hooks, but further reduction of the pile height has been limited by the finite depth of the needle plate fingers.
Substantially low pile tufted fabrics have been produced by utilizing a needle plate such as that disclosed in U.S. Pat. No. 4,503,787 of Charles W. Watkins, dated Mar. 12, 1985, for "LOW PILE NEEDLE PLATE FOR TUFTING MACHINE" and which has been assigned to the assignee of this application. The above Watkins low pile needle plate has been utilized very successfully in the production of low cut pile tufted fabrics by in-line multiple needle tufting machines. In order to successfully produce low pile tufted fabric with the Watkins needle plate in a staggered needle tufting machine, the tops of the tufting hooks must be high enough to support the backing fabric. As the tufting hooks are lowered, the portions of the backing fabric penetrated by the rear needles over the tufting hooks is not adequately supported, even though the portions of the backing fabric stitched by the front needles are adequately supported by the notched needle plate.
It has been discovered that by laterally and reciprocably shifting the moving backing fabric relative to the stationary needle plate of the Watkins U.S. Pat. No. 4,503,787 in an in-line tufting machine, dense pile tufted fabric of superior quality is produced. However, when the mechanism for laterally shifting the backing fabric is incorporated with the Watkins low pile needle plate in a staggered needle tufting machine, the portions of the backing fabric stitched by the rear needles are not adequately supported.
Dense tufted pile fabric in which there is relative lateral movement between the backing fabric and the needles has been produced in accordance with one or more of the following U.S. Pat. Nos.
______________________________________ 3,301,205 R. T. Card Jan. 31, 1967 3,577,943 Watkins May 11, 1971 4,440,102 R. T. Card, et al Apr. 3, 1984 ______________________________________
In the above R. T. Card U.S. Pat. No. 3,301,205, the relative movement between the fabric and the needles is attained by laterally shifting the needle plate in order to form loop pile.
In the Watkins U.S. Pat. No. 3,577,943, the relative movement is attained by laterally shifting the needle plate for producing cut pile tufted fabric. The needles are programmed to penetrate the backing fabric while the fabric is laterally shifting.
In the R. T. Card, et al, U.S. Pat. No. 4,440,102, the relative lateral movement is attained by laterally shifting the needle bar relative to the fabric. The needles penetrate the fabric as the needles are laterally shifting.
Although Watkins (U.S. Pat. No. 3,577,943) discloses relatively short needle plate fingers 30 projecting rearwardly from the free rear edge of the needle plate 28, nevertheless, this needle plate is used in combination with an in-line multiple needle tufting machine. Although Watkins, in Col. 4, lines 28-32, states that it is contemplated that his machine can be used with staggered needles, nevertheless, there is no teaching in the Watkins patent of any structure which would adequately support the portions of the base fabric penetrated by the rear needles, as well as the front needles.
A conventional "jute shifter" has been utilized in jogging or laterally shifting the base fabric in small increments in combination with conventional needle plates having conventional long and thick needle fingers, with limited success. Both the large size of the needle fingers and the fact that the loops are held on the looper hooks while the fabric is laterally shifted, substantially restrain the lateral movement of the base fabric and therefore the formation of the zig-zag stitching to produce dense tufted pile fabric. Moreover, this problem is compounded where the needle fingers are conventionally longer to project between staggered rows of needles, and particularly in fine gauge staggered needle tufting where the yarns become quite crowded and bind upon the needle plate fingers.